1. Field of the Invention
The present invention relates to a movement direction determination apparatus for non-contact determination of the movement direction of an object.
2. Description of the Related Art
FIG. 10 is a schematic view of a rotation-direction determination apparatus for use in assembly inspection for spindle motors and the like. A rotary spindle motor 1 is assembled with geometric structures, such as screws 2. A CCD (charge coupled device) camera 3 captures images of a position at which the screws 2 pass during the rotation of the spindle motor 1 and transfers the images to a personal computer 4. The personal computer 4 then analyzes the images at a sufficiently high sampling frequency relative to the rotation frequency of the spindle motor 1. As a result, images as shown in FIG. 11A are obtained for clockwise rotation, while images shown in FIG. 11B are obtained for counterclockwise rotation.
Based on such a series of images, a determination can be made as to in which direction the images of the screws 2 move. In general, this direction determination is made through analysis with software installed on the personal computer 4, and the result is then displayed.
In the above example of the related art, geometric structures, such as the screws 2, need to exist on rotating objects or moving objects in order to determine the movement directions.
When, however, the current trends toward higher productivity and lower cost are considered, it is problematic to use the screws 2 and the like for the assembly. Thus, it is considered that press fitting or the like, which is a less expensive assembly technique, will be adopted in the future. In such a case, geometric structures cannot be expected to exist on rotating objects, such as the spindle motor 1, thus making it difficult to determine the movement of the shape captured in images.